SalesForce Certified JavaScript Developer I Certified JavaScript Developer I Free Practice Test — 30 Questions

Question 1

A company is developing a web application that integrates with Salesforce to manage customer data. The application needs to retrieve customer records based on specific criteria and update them in real-time. Which approach would be the most efficient for ensuring that the application can handle a high volume of requests while maintaining data integrity and minimizing latency?

Accepted Answer

Utilize Salesforce's Bulk API for batch processing of records.

Question 2

A company is developing a web application that integrates with Salesforce to manage customer data. The application needs to retrieve customer records based on specific criteria and update them in real-time. Which approach would be the most efficient for ensuring that the application can handle a high volume of requests while maintaining data integrity and minimizing latency?

Accepted Answer

Utilize Salesforce's Bulk API for batch processing of records.

Question 3

In a JavaScript application, you are tasked with extracting specific properties from a user object that contains various details about a user. The user object is structured as follows:

Accepted Answer

javascript

Question 4

In a modern JavaScript application, you are tasked with implementing a function that takes an array of user objects and returns a new array containing only the users who are active and have a specified role. You decide to use ES6+ features to achieve this. Which of the following implementations correctly utilizes ES6+ features such as arrow functions, destructuring, and the `filter` method?

Accepted Answer

`const getActiveUsersByRole = (users, role) => users.filter(({ isActive, userRole }) => isActive && userRole === role);`

Question 5

In a web application, you have a list of user objects, each containing properties such as `name`, `age`, and `isActive`. You need to modify the `isActive` property of each user based on their `age`. Specifically, if a user\'s age is greater than or equal to 18, `isActive` should be set to `true`; otherwise, it should be set to `false`. Given the following JavaScript code snippet, which correctly modifies the `isActive` property for each user in the `users` array?

Accepted Answer

javascript

Question 6

In a JavaScript application, a developer is tasked with optimizing memory usage when handling large datasets. The application frequently creates and discards objects, leading to potential memory leaks. The developer decides to implement a memory management strategy that includes both garbage collection and manual memory management techniques. Which approach would best help in minimizing memory leaks while ensuring efficient memory usage?

Accepted Answer

Implementing weak references for objects that are not critical to the application's functionality.

Question 7

In a web application, you are tasked with fetching user data from an API and then processing that data to display it on the user interface. You decide to use the `async/await` syntax in JavaScript to handle the asynchronous operations. If the API call takes 2 seconds to respond and the data processing takes an additional 1 second, what will be the total time taken to fetch and process the data if the `await` keyword is used correctly in the function?

Accepted Answer

3 seconds

Question 8

In a JavaScript application, you are tasked with implementing a function that calculates the factorial of a number. You have two options for defining this function: using a function declaration or a function expression. If you choose to use a function expression, what implications does this have for the scope and hoisting of the function, especially when considering that the function will be called before its definition in the code?

Accepted Answer

The function will not be hoisted, and calling it before its definition will result in a TypeError.

Question 9

In a web application, a developer is implementing a feature that requires a user to be both logged in and have a verified email address to access premium content. The developer uses logical operators to check these conditions. If the user is logged in (represented by the variable `isLoggedIn`) and their email is verified (represented by the variable `isEmailVerified`), the application should grant access. What will be the outcome of the logical expression `isLoggedIn && isEmailVerified` if `isLoggedIn` is `true` and `isEmailVerified` is `false`?

Accepted Answer

The user will not gain access to the premium content.

Question 10

In a web application, a developer is implementing a feature that requires a user to be both logged in and have a verified email address to access premium content. The developer uses logical operators to check these conditions. If the user is logged in (represented by the variable `isLoggedIn`) and their email is verified (represented by the variable `isEmailVerified`), the application should grant access. What will be the outcome of the logical expression `isLoggedIn && isEmailVerified` if `isLoggedIn` is `true` and `isEmailVerified` is `false`?

Accepted Answer

The user will not gain access to the premium content.

Question 11

In a software application, you have an array of user objects, each containing a name and an age property. You need to create a new array that contains the names of users who are older than 18, and then transform those names into uppercase. Given the following array of user objects:

Accepted Answer

javascript

Question 12

In a web application, a developer is implementing a function that fetches user data from an API. The function uses a try...catch statement to handle potential errors during the fetch operation. If the fetch fails due to a network error, the catch block is designed to log the error and return a default user object. However, the developer is unsure about the best way to structure the catch block to ensure that the application can gracefully handle different types of errors, such as network issues or unexpected response formats. Which approach should the developer take to effectively manage these scenarios?

Accepted Answer

Use a single catch block to log the error and return a default user object, while also checking the error type within the block to handle specific cases.

Question 13

In a JavaScript application, a developer is debugging a function that calculates the factorial of a number. The function uses a recursive approach, and the developer has set breakpoints at the beginning of the function and before the return statement. When the developer steps through the code, they notice that the function is called multiple times with the same argument. What is the most likely reason for this behavior, and how should the developer address it to optimize the function?

Accepted Answer

The function is not using memoization, leading to repeated calculations for the same input.

Question 14

In a web application, you are tasked with creating a function that calculates the total price of items in a shopping cart. Each item has a price and a quantity. The function should also apply a discount of 10% if the total price exceeds $100. Given the following code snippet, identify the correct implementation of the function that adheres to these requirements:

Accepted Answer

javascript

Question 15

In a JavaScript function, you declare a variable using `let` inside a block scope and then attempt to access it outside of that block. What will be the outcome of this operation, and how does it illustrate the differences between block scope and function scope in JavaScript?

Accepted Answer

The variable will be undefined outside the block scope due to its limited visibility.

Question 16

In a JavaScript function, you declare a variable using `let` inside a block scope and then attempt to access it outside of that block. What will be the outcome of this operation, and how does it illustrate the differences between block scope and function scope in JavaScript?

Accepted Answer

The variable will be undefined outside the block scope due to its limited visibility.

Question 17

In a Lightning Web Component (LWC), you are tasked with creating a dynamic form that allows users to input their details. The form should validate the input fields and display error messages if the inputs do not meet specific criteria. You decide to implement a custom validation method that checks if the input is empty and if the email format is correct. Which approach would best ensure that the validation logic is reusable and maintainable across different components?

Accepted Answer

Create a utility JavaScript file that exports the validation functions and import this file in any component that requires validation.

Question 18

In a JavaScript module system, you are tasked with creating a utility module that exports a function to calculate the area of a rectangle. You also want to import this function into another module to use it for calculating the area of multiple rectangles with different dimensions. If the utility module is named `geometry.js` and the function is exported as `calculateArea`, which of the following import statements correctly imports the `calculateArea` function into your main module?

Accepted Answer

`import { calculateArea } from './geometry.js';`

Question 19

In a JavaScript function, you define a variable `counter` within an outer function and then create an inner function that increments this `counter`. If you invoke the inner function multiple times, what will be the final value of `counter` after three invocations, assuming it starts at 0? Consider the following code snippet:

Accepted Answer

javascript

Question 20

In a Salesforce Lightning Component, you are tasked with creating a dynamic user interface that updates based on user input. You decide to implement a component that allows users to select a product category, which then dynamically populates a list of products within that category. To achieve this, you need to utilize the Lightning Data Service (LDS) for data binding and ensure that the component adheres to best practices for performance and maintainability. Which of the following strategies would be most effective in ensuring that the component efficiently updates the product list while minimizing server calls?

Accepted Answer

Use the `@wire` service to fetch the product list based on the selected category and implement a caching mechanism to store previously fetched results.

Question 21

In a web application, a developer needs to select multiple elements from a list of items displayed on a webpage. The items are represented as `` elements with a common class name `item`. The developer wants to apply a specific style to all selected items using JavaScript. Which method would be the most efficient way to select all elements with the class name `item` and apply a style change to them?

Accepted Answer

`document.querySelectorAll('.item').forEach(item => item.style.color = 'blue');`

Question 22

In a JavaScript application, a developer is debugging a function that calculates the factorial of a number. The function is set with breakpoints at various lines to inspect the flow of execution and variable states. When the developer steps through the code, they notice that the variable `result` is not updating as expected during the recursive calls. Which of the following scenarios best describes a potential issue that could arise during step-through debugging in this context?

Accepted Answer

The developer may have forgotten to return the result of the recursive call, causing the function to always return the initial value of `result` instead of the computed factorial.

Question 23

In a collaborative software development environment, a team is working on a complex JavaScript application. Each developer is responsible for different modules, and they need to ensure that their code is understandable and maintainable by others. Which practice is most effective for achieving clarity and facilitating collaboration through documentation and code comments?

Accepted Answer

Writing clear and concise comments that explain the purpose of functions, the parameters they accept, and the expected return values, while also including examples of usage.

Question 24

In a Lightning web component, you are tasked with creating a dynamic form that adjusts its fields based on user input. The form should include a dropdown that, when a specific option is selected, reveals additional input fields for user details. Which approach would best facilitate this dynamic behavior while adhering to the principles of Lightning Base Components?

Accepted Answer

Utilize the `lightning-combobox` for the dropdown and conditionally render additional `lightning-input` components based on the selected value using the `if:true` directive in the template.

Question 25

A software development team is tasked with creating a new feature for an e-commerce platform that allows users to apply discount codes during checkout. The team needs to write test cases to ensure that the discount code functionality works correctly under various scenarios. Which of the following test cases would be most effective in validating the discount code feature?

Accepted Answer

Test the application of a valid discount code that meets all criteria and verify that the total price reflects the discount correctly.

Question 26

In a JavaScript function, you are tasked with managing a list of user roles. You need to declare a variable to hold the roles that can be modified later, while also ensuring that the variable cannot be redeclared within the same scope. Additionally, you want to create a constant variable for the maximum number of roles allowed, which should not change throughout the execution of the program. Given these requirements, which declaration method would be most appropriate for each variable?

Accepted Answer

Use `let` for the roles variable and `const` for the maximum roles variable.

Question 27

In a web application, a developer is debugging a complex issue where the output of a function is not as expected. The developer decides to use various console methods to track the flow of data and identify where the problem lies. Which console method would be most appropriate for logging an object while also allowing the developer to inspect its properties interactively in the console?

Accepted Answer

console.dir()

Question 28

In a web application, you have a section of HTML that contains multiple elements with the class name \"item\". You need to retrieve the first element with this class and change its background color to blue. Additionally, you want to ensure that the change only affects the first element retrieved, regardless of any other elements with the same class name. Which method would you use to achieve this, and how would you implement it in JavaScript?

Accepted Answer

Use `document.getElementsByClassName('item')[0].style.backgroundColor = 'blue';`

Question 29

In a web application, a developer is tasked with creating a dynamic greeting message that incorporates a user\'s name and the current date. The developer decides to use template literals to construct the message. Given the following code snippet, identify the output of the `greeting` variable:

Accepted Answer

javascript

Question 30

A software development team is implementing unit tests for a new JavaScript module that handles user authentication. The module includes functions for registering users, logging in, and logging out. The team decides to use a test-driven development (TDD) approach. They write unit tests for the `registerUser` function, which takes a username and password, checks if the username is already taken, and then creates a new user if it is not. The team has identified three potential scenarios to test: (1) registering a new user with a unique username, (2) attempting to register a user with an already taken username, and (3) registering a user with a password that does not meet the security criteria (e.g., too short). Which of the following best describes the expected outcomes of these unit tests?

Accepted Answer

The first test should pass, while the second and third tests should fail, indicating that the function correctly handles unique usernames and enforces password security.

SalesForce Certified JavaScript Developer I Certified JavaScript Developer I Free Practice Test — 30 Questions

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